Learning to see

Nature Neuroscience

April 11, 2011

On regaining their sight, congenitally blind children are initially unable to visually recognize an object that they have previously only touched, reports a study published this week in Nature Neuroscience. These results suggest that, in a sense, we must learn to see: people learn the correspondence between how objects look and how they feel, and this ability is not innate.

Richard Held and his colleagues studied a group of eight- to 17-year-old patients treated by Project Prakash, a humanitarian and scientific effort to treat curable blindness in India, where, like in many developing countries, medical services are often inadequate. All of the participants had been blind from birth because of congenital cataracts or an opaque cornea ― the usually transparent front of the eye. After cataract removal or a corneal transplant, these participants were asked to feel a building brick, and then asked to match the brick they had felt with one of two bricks they were shown. Though this task is easy for most people, these patients were unable to correctly match the blocks they felt to what they only saw. However, when some of these children were tested as little as five days later, their performance had improved substantially.